Thursday, June 11, 2015

Fiat 500X Suspension and Chassis

The Fiat 500X is a crossover that drives more like a sports sedan than an SUV. This is due to the use of a sophisticated 4-wheel independent suspension with special tuning and an extremely rigid chassis. Fiats are born in the city of Torino, located at the base of the Italian Alps. To excel in this mountainous local, Italian cars are expected to have nimble, predictable and safe handling. The typical mushy, vague SUV handling characteristics don't cut it in this environment. To live up to its Italian heritage, Fiat ditches the truck derived suspension a traditional SUV uses for something different. The following is a look at the Fiat 500X suspension and chassis.

Koni Shock Absorber Technology
The Fiat 500X uses Koni frequency selective damping (FSD) technology in its front strut and rear shock absorbers. Koni is a maker of premium shock absorbers and are typically found on high end and exotic cars. Koni FSD technology gives the 500X a high level of suspension control, yet still delivers a comfortable ride.

Fiat 500X Front Suspension
Up front, the Fiat 500X uses a MacPherson Strut suspension system that is known for its compact dimensions and low unsprung weight. Weight is a critical element in suspension design as having a heavy suspension system inhibits the tire's ability to maintain contact with the road. A suspension that is light can react quicker to road surface irregularities, which is what you want on rough mountain roads. The front suspension on the Fiat 500X has been optimized for improved geometry and elastokinematic* characteristics with the goal of enhancing steering response and handling.

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An interesting bit of trivia is while the suspension design is typically referred to as MacPherson strut, named after a Ford engineer who popularized the design in the late 1940's. Fiat originally patented a strut type suspension some 20 years earlier. The Fiat Strut uses a wishbone lower control arm to anchor the suspension strut, while the MacPherson design employs a single I-shaped lower control arm and a sway bar to do double duty as an anti-roll bar and suspension locating device. The Fiat way of anchoring the control arm actually offers a more precise way of locating the wheels during suspension movement and is the style most commonly used or adapted for modern use.

Other notable features of the Fiat 500X front suspension are:

A high-strength-steel front cross member that increases the car's rigidity and is integrated into the third load path for improved crash performance.

Lower control arms are also made from high-strength-steel for long life. Cars equipped with All-Wheel-Drive have control arms made with a double thickness of high-strength-steel for additional ruggedness.

The anti-roll bar end links that connect to the struts are made of composite material and not the commonly used steel. This solution is typically reserved for premium applications and has been carefully optimized to balance suspension and chassis forces. Additionally, the design is effective at filtering out vibrations which improves ride quality. The anti-roll bar diameter is 25 mm.

The strut features an offset coil spring that reduces side load forces acting on the strut which results in improved absorption of slight unevenness in the road surface. Coil springs made of high-strength-steel keeps weight down.

Rear suspension support or cradle has been specifically optimized for strength/weight ratio depending on whether front-wheel-drive or all-wheel-drive.

As in the front, coil springs are offset along the thrust angle for improved rough road performance. A coil spring isolator is used at their base for enhanced quietness. Rear coil springs are also made of high-strength-steel.

Rear struts feature extra rigidity for improved ride quality.

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Fiat 500X Chassis
Tying the suspension together is a stiff chassis. To effectively tune a suspension for precise handling, a chassis that doesn't flex is vital. The chassis of the Fiat 500X consists of 70 percent high-strength-steel and a good amount of aluminum and magnesium. The extremely rigid chassis is the perfect host for the flexible suspension. Along with being strong, high-strength-steel is also light and the results can be seen when looking at the car's relatively light 2,967 - 3,278 lbs curb weight.

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The results are a crossover utility vehicle that is fun to drive, and has great handling and high-speed stability. Exactly what is needed in the Alps or a brisk drive on your favorite local road.

Disclaimer

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